NUTRITION IN THE LIVING BEING. "' 2g3 



physical characters of the body — solidity in the 

 crystal, semi-fluidity in the cellular protoplasm. If 

 we compare the inorganic liquid matter with the 

 semi-fluid organized matter, we recognize that the 

 addition of substance takes place in the same manner 

 in each — i.e., by interposition. If we add a soluble 

 salt to a fluid, the molecules of the salt separate 

 themselves and interpose themselves between those 

 of the fluid. There is, therefore, nothing especially 

 mysterious or particularly vital about the process of 

 intussusception. Applied to fluid protoplasm, it is 

 merely the diffusion that ordinarily occurs in mixed 

 liquids. 



